#all{
    border: 1px solid red;
    width: 600px;
    margin: 0 auto;
}
#top{
    position: relative;
    height: 65px;
    background: #EEEEEE;
}
/*定义logo大小及位置*/
#logo{
    height: 40px;
    position: absolute;
    margin: 15px 0 0 465px;
}
#top li{
    list-style-type: none;
    float: left;
    margin: 15px 0 20px 20px;
    text-align:center;
    width: 200px;
    height: 50px;
    font-size: 20px;
    font-weight: 600;
    line-height: 50px;
}
/*#btn_1{*/
/*    margin: 15px 0 0 15px;*/
/*}*/
/*#btn_2{*/
/*    position: absolute;*/
/*    margin: 15px 0 0 15px;*/
/*}*/
#li_1,#li_2{background: #EAEAEA;border: none;}
#li_1:hover,#li_2:hover{background: #EAEAEA;border: none}

.xian{display: block;}
.yin{display: none;}
#mid{
    height: 205px;
    background: blanchedalmond;
}
#mid_content{

}

#bot{
    height: 195px;
    background: cornflowerblue;
}